Noisy diff, any way to fix it?

[CorvallisBMW]

My diffs makes a whiring noise, sounds exactly like a noisy fuel pump. I've tried Redline 75w-90 gear oil (both the regular and the 'NS' stuff) and have gotten no luck. Anyone ever had this situation before and been able to remedy it?

[jlevie]

Differential whine will be from improper clearance between the ring gear and pinion, bad bearings, or damage to the gears. A tear down and rebuild is one solution, but a used replacement will be cheaper.

[reelizmpro]

There's always 80w-140. Beyond that... swap it out or rebuild.

[hoveringuy]

I've got noise coming from mine, too. Not a gear whirring sound but more like brakes dragging. It corresponds exactly to wheel speed, have nothing to do with turning.

I suspect it could be the output bearing.

Are those difficult to replace? Anyone done it?

[CorvallisBMW]

mine has been getting louder over the last 2 months or so, I really need to replace it.

[hoveringuy]

mine has been getting louder over the last 2 months or so, I really need to replace it.

My question, can't you just replace the bearings??

[CorvallisBMW]

I don't know if it's the bearings, clutch packs, or what. I have no idea how to replace bearings in a diff, I've never heard of anyone short of a diff rebuilding shop doing it. What does it take? Anyone know? Heck, where do you even buy diff parts? Can you ge them from the dealer, or are they going to try and sell me a whole diff?

[reelizmpro]

I've seen it done. My buddy had to source the TIMKEN bearings that would work. It was kind of tricky changing them out and then dealing with the seals. I would try the thicker 80w-140 fluid first. That's what I did and the noise was gone instantly. You'll probably lose a few more HP though.

[Liam]

My question, can't you just replace the bearings??

It's a little more difficult than that (requires some special tooling and skill to set up a final drive).

I have heard that Lucas oil stabilizer will shut them up for a while though.

[CorvallisBMW]

Right, I'll try 80w-140 with some Lucas and see if that helps. It's getting really annoying

[hoveringuy]

I put my 3.73 back in.

Ah... Quiet!

I got the 3.25 from "Peter" in North Seattle a few days ago who assured me it was a quiet diff. In reality, it had a continuous dragging sound and a tight spot. I'm almost certain one of the output bearings is spalled.

Suprisingly, I have not been able to raise Peter on the phone. Doesn't return my calls, etc. Just shows me that he KNEW it was bad!

I'll take it apart in the next day or two.

[Liam]

Right, I'll try 80w-140 with some Lucas and see if that helps. It's getting really annoying

Use the "Oil Stabilizer... the thick shit... not the other stuff" (what other stuff I don't know).

I've never tried this but the Mercedes mechanic in my shop swears by it.

[hoveringuy]

Partially disassembled...

Both output bearing races have spalling. One very slight, the other more noticeable.

When tipping the empty case back and forth there's a metalic sound like rolling ball bearings from the input shaft. I don't have the 30mm to take the input shaft off yet, I don't think any oil product would have quieted this thing down!

[CorvallisBMW]

I put in 1/2 85w-140, 1/2 Lucas Oil Stabilizer. It seems to have quieted down a bit, but it's still very noticeable.

Where are you getting your parts from to rebuild the diff?

[hoveringuy]

I put in 1/2 85w-140, 1/2 Lucas Oil Stabilizer. It seems to have quieted down a bit, but it's still very noticeable.

Where are you getting your parts from to rebuild the diff?

Me? Pelican, most likely.... after I go to WalMart to buy a bat to beat the too the tool that sold the POS to me.

The metalic sound was actually MOST OF THE ALLEN HEADS holding the limited slip package together! They were all sheared off and were nicely tumbled from how many miles of banging around in there?

So, I'll need to drill and remove those bolts, but I won't be rebuilding the LS unit.

How does one remove the input shaft? With a press??